1. Field of the Invention
This invention relates to a manipulator for engaging a pouring tube with a discharge gate valve of a pouring ladle, which manipulator comprises a boom, which is pivoted on a horizontal axis and serves to hold the pouring tube, and a turning cylinder, which is interposed between the boom and an abutment.
2. Description of the Prior Art
To prevent an uncontrolled discharge of the molten steel from a pouring ladle into a succeeding tundish, a pouring tube forced against the bottom outlet of the pouring ladle serves to conduct the molten steel from the pouring ladle into the tundish. By means of a manipulator that pouring tube is engaged with suitable protruding centering means of the discharge gate valve of the pouring ladle and as the discharge gate valve is opened the pouring tube is moved to a position in front of the bottom outlet of the ladle. For that purpose the manipulator comprises a boom, which serves to hold the pouring tube and which is pivoted on a horizontal axis and adapted to be adjusted by means of a pivoting cylinder. That pivoting cylinder can be used to position the pouring tube, which is carried by the boom, and to force the pouring tube against the centering means of the discharge gate valve of the pouring ladle with a pressure force which is sufficient for the pouring operation. But those known manipulators have the disadvantage that the position of the boom or of the turning cylinder will not indicate to the operator of the manipulator whether the pouring tube is merely held against the discharge gate valve in a proper position or is forced against that valve by the force which is required for the pouring operation. For this reason the discharge gate valve may be improperly operated. If the discharge gate valve of the pouring ladle is operated before the pouring tube is forced against the discharge gate valve, molten steel can escape in an uncontrolled manner bewteen the discharge gate valve and the pouring tube. It must be taken into account in that connection that even when the pouring tube is subjected to the pressure force that is required for the pouring operation the boom must be shifted to move the pouring tube in unison with the discharge gate valve and the pouring ladle.
From Published German Application No. 3,425,676 it is known to replace the pivoting cylinder by an energy-storing spring device, which is stressed by hand via a toggle joint to force the pouring tube by means of the boom against the discharge gate valve of the pouring ladle. But because the toggle joint cannot be used to position the boom, the boom must be pivoted directly on the pouring ladle. As there is no defined intermediate position of the boom between its lower position of rest and its operating position, in which the pouring tube is forced against the discharge gate valve, the above-mentioned problem which arises in the operation of manipulators having a boom which is positionable by means of a pivoting cylinder does not arise.